Patent Application
20060215677
This invention relates to network communication systems. More particularly, it relates to the use of frame control blocks to describe data packets. It also relates to the manipulation of frame control blocks to optimize the format for different uses of some frame control block fields and for maintaining consistent formats between low and high end configurations.
With the worldwide interconnection of computers through the Internet, bandwidth is considered to be a critical resource. The increasing amount of network traffic driven by the net and other emerging applications is straining the capacity of network infrastructures. To keep pace, better technologies are constantly being sought to support and manage traffic growth.
The discussion which follows presupposes knowledge of network data communications, and switches and routers as used in communication networks. A fundamental understanding of bits, bytes, packets and frames in network communication is also helpful for the discussion that follows.
A switching network has switching points or nodes for transmission of data among senders and receivers connected to the network. The switching performed by these switching points is, in fact, the action of passing packets or “frames” of data received by a switching point or node to a further node in the network. This switching action is the means by which communication data is moved through a packet switching network.
Each node may comprise a packet processor configured to process the packets or frames of data. The packet processor may contain a data storage unit, such as a DRAM, configured with a plurality of buffers to store frame data. Each frame of data may be associated with a frame control block configured to describe the corresponding frame. Each frame control block may be associated with one or more buffer control blocks, wherein each buffer control block associated with a frame control block may be associated with a buffer in a data storage unit. Buffer control blocks and frame control blocks comprise various fields of information, wherein these fields are each supplied by a separate memory in the packet processor. Thus, the fields of information in the frame control blocks and the buffer control blocks may be obtained by accessing a separate memory in the packet processor.
The present invention relates to a communication network apparatus, such as the type used to link together information handling systems or computers of various types and capabilities, and to counterparts of such apparatus. In particular, the invention relates to the improved and multifunctional interface device and to methods of operating such a device to improve the data flow handling capability of network switches.
Throughout this description, the following terms are described as noted
The present invention relates to the structuring of frame control blocks in a flexible format that allows frame description and manipulation. The frame control block describes a frame which is a discrete packet of data. The frame control blocks are organized to efficiently describe in different ways a data packet that can be chained in different types of queues, or can operate without chaining outside a queue. In this manner, the bandwidth of a control store can be optimized. The invention applies to buffer control blocks as well as frame control blocks.
Because messages are transient by nature, the present invention also reuses a field of a message to hold working information during a packet process. In addition, functions, such as ATM segmentation and reassembly, can reuse part of a frame control block when a frame is not ready for data movement. The invention supports system scalability by widening frame control block memory.
The invention also relates to a network communication system having an integrated circuit that provides capabilities for frame control blocks in a network architecture. Each frame control block contains information describing and managing a frame or packet of data. The FCB has a flexible format for a specified description and manipulation of the associated frame. The flexible format comprises multiple fields in one or more words, the fields containing information based upon the location of the frame. When the frame is in the output queue of a network processor, the processor contains a reference frame control block address for egress of the frame to a line port and a multicast identification for ingress from an output queue to a switch port. The reference frame control block address and multicast identification counter both have multicast capabilities. Most often, the frame is to be unicast, requiring an FCB format using two words. On the other hand, if the frame is to be multicast on the output line port or switch port, a third word is used.
When the frame is in the input queue of a network processor, the format does not require access to a third word, and does not require multicast capabilities or an end byte position locator. This format is useful for asynchronous transfer mode segmentation and reassembly and internet protocol reassembly for describing and controlling discrete data frames. In addition to the structure, the invention likewise relates to the method of using the frame control blocks and buffer control blocks in a flexible format to allow more efficient description and manipulation of frames.
The invention also relates to an article of manufacture which comprises a medium containing a computer readable program. When executed on a computer, the program causes the computer to execute operations that serve to increase the bandwidth available for describing and controlling data packets within a computer. The program provides commands for frame control blocks and buffer control blocks in the network processor. It also provides each control block with a description and management of a data packet for each frame control block. It provides each control block with a flexible format comprising multiple fields containing information based upon the location of a data packet.
The drawings are presented to facilitate the understanding of the present invention without intending to limit the scope thereof. These drawings are briefly described as follows:
The invention defines a format of frame control blocks that is both flexible and efficient in a communication system. An FCB is associated with each packet handled by the network processor and contains all the control information needed to describe and manage the packet (e.g. chaining pointer, packet length, etc . . . ). The frame control block may contain a next pointer field that gives the address of the next FCB in the queue. It does not, however, include any additional information relating to the next frame in a queue, but to the current frame that it defines and over which it exercises control.
Turning now to the drawings,
The network processor includes buffering and queueing structures. A packet can be chained in one of several queues, or it can be totally outside of any queue, for example when it is owned by some control logic that works on the packet (look-up, modification . . . ). Depending on the location of the packet, different control information may be relevant or not. This is why the FCB format is organized so that some fields can be used in different ways as shown in
Another important feature of the FCB format is that FCBs can be used for other purposes. This is efficient because the same control structure is used for other functions. In particular, no additional free queue is needed (only manage a single free queue of FCBs). The functions that are contemplated are ATM segmentation and reassembly, and IP reassembly.
The present invention can be realized in hardware, software, or a combination of the two. Any kind of computer system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware and software could be a general purpose computer system that, when loaded and executed, controls the computer system such that it carries out the methods described herein. The present invention can also be embedded in a computer program product, which comprises all the features enabling the implementation of the methods described herein, and which, when loaded in a computer system, is able to carry out these methods.
Computer program instructions or a computer program in the present context mean any expression, in any language, code (i.e., picocode instructions) or notation, of a set of instructions intended to cause a system having an information processing capability to perform a particular function either directly or after either or both of the following occur: (a) conversion to another language, code or notation; (b) reproduction in a different material form.
While the invention has been described in combination with specific embodiments thereof, there are other alternatives, modifications, and variations that are likewise deemed to be within the scope thereof. Accordingly, the invention is intended to embrace all such alternatives, modifications and variations as fall within the spirit and scope of the appended claims.
